The real argument for PDF
A Word document looks slightly different on every machine. That is not Word's fault: the file only states which font should be used. If the recipient does not have it, their computer picks something similar. Lines break differently, paragraphs shift, two pages become three.
A PDF carries its fonts inside. That makes it the right format whenever appearance matters: applications, quotes, contracts, anything printed or signed.
The route
Use Word to PDF to turn a DOC or DOCX file into a PDF. Fonts, paragraphs and page breaks carry over.
The same principle applies to spreadsheets via Excel and slides via PowerPoint.
The three places it snags
Unusual fonts. A font installed only on your machine may get substituted during conversion. If it matters, stick to common ones. For a job application an ordinary font is the better choice anyway.
Headers and footers. They like to drift when page margins are tight. A look at the first and last page of the finished PDF is worth the minute.
Tables at a page boundary. A table that reaches just past the page end gets broken. In Word this often goes unnoticed; in the PDF the header row then sits alone on the previous page.
Check before sending
The most reliable check is the simplest one: open the finished PDF and look at it the way the recipient will. Does the page count match what you expected? Is the signature still on the same page as the closing line?
If a page turned out redundant, Delete pages removes it. And if you still need to sign, Sign PDF does it in the browser, without printing and scanning.
In short
PDF carries its fonts, Word does not. That is why the recipient sees what you see. Unusual fonts, headers and tables at page boundaries are the typical trip hazards, and one look at the finished document settles them.